<p>got a 78 on the 2008 practice test. Hope the real thing is like that. Didn’t do the FRQs yet.</p>
<p>Sorry, I’ve been away from this thread for awhile. </p>
<p>Approximately 34 days remaining until the exam.</p>
<p>Describe the basic structure of a steroid molecule.</p>
<p>
</p>
<p>Lipid; Four-fused carbon ring usually with various other groups attached around it</p>
<p>Can someone explain depolarization/action potential/hyperpolarization involving neurons to me? I don’t think I’m understanding it too well. </p>
<p>Thanks!</p>
<p>And before I forget, mifune: Congratulations on getting into Harvard (and of course, all your other acceptances)!</p>
<p>hi, im having problems with this questions. will somebody please explain this question to me por favor! its from the 1999 ap exam
18. in a mesophyll cell of a leaf, the synthesis of atp occurs in which of the following?
I. ribosomes II. mitochondria III. chloroplasts
a. I only b. II only c. III only d. II and III e. I, II, III</p>
<p>im between c & d :/</p>
<p>Synthesis of ATP occurs in the chloroplasts and mitochondria.</p>
<p>Okay, so depolarization occurs when you get an influx of Na+ ions making the action potential have a more positive charge. For example, a non active potential is usually about -70 mV, but when depolarization occurs and Na + enter into the membrane, the voltage goes down. The reason it goes down is because a cation, which exhibits a positive charge fluxes into the membrane. This can also happen by Ca+ entering the cell as well.</p>
<p>Hyperpolarization, on the other hand, is when you get a more negative charge. This can either happen by the exit of K+ ions form the membrane, which leaves the membrane with less positive ions than before and thus leads to a lower mV. Another way hyperpolarization can occur, is by an influx of Cl-. Since Cl is an anion and has a negative charge, it will make the mV more negative.</p>
<p>im having problems with the allosteric enzymes. not sure of what the allosteric activator and allosteric inhibitor does… and if anybody has the cliffs AP bio book, could you take a look at the two questions on the allosteric enzymes on page 25 and explain why the answers are what they are? i read the explanations in the back but i still dont understand it.</p>
<p>I just took the 2008 test and my results are quite depressing. I received a 53/100; FAIL. The worst part of it all is that I will be majoring in Biology and hope to matriculate into medical school after my undergraduate studies.</p>
<p>
</p>
<p>Thanks!</p>
<p>
</p>
<p>In question 2, as E accumulates during the forward reaction, it will inhibit the production of D (given in the prompt). Thus, the reverse reaction from D to C will increase until chemical equilibrium is reached between the two reagents. At that point, the net production of D will be zero (by definition of chemical equilibrium). So (letter choice) C is the correct answer. </p>
<p>In question 3, E serves as an allosteric effector that inhibits C. As E accumulates, it will prevent the forward reaction and therefore the production of the enzymes D, E, J, K, and L will decrease. Thus, (letter choice) E is the correct answer.</p>
<p>As for descriptions of allosteric enzymes, activators induce an enzyme’s active form (by binding to the active site for the substrate) while inhibitors bind to the enzyme’s inactive form.</p>
<p>Please inform me if you need further clarification. I hope that did not make things worse. :)</p>
<p>[ul]Master genes that control the expression of other genes responsible for anatomical structures are called
[list]<a href=“A”></a> mesoglea
<a href=“B”></a> acrosomes
<a href=“C”></a> Hox genes
<a href=“D”></a> cortical genes
<a href=“E”>*</a> parthenogenetic genes[/ul][/list]</p>
<p>[SparkNotes:</a> SAT Subject Test: Biology: Test Center](<a href=“http://testprep.sparknotes.com/testcenter/sat2/biology/index.epl]SparkNotes:”>http://testprep.sparknotes.com/testcenter/sat2/biology/index.epl)</p>
<p>^Hi all. I just took test 1 over there^. </p>
<p>Are a lot of those questions bad? Like the red cabbage, red/white flies, and the chart on the last page? </p>
<p>I got all the objective questions right, but some of the lab-related questions seem bad</p>
<p>Hox genes. Almost perfectly conserved between vertebrates, even reasonably similar between humans and the fruit fly. You sprout parts in the wrong places if you have bad Hox genes. :S</p>
<p>Describe the kinds of junctions found between animal cells.</p>
<p>Tight junctions- protein complexes that join adjacent cells together, usually formed between epithelial cells which line organs, prevent leakage</p>
<p>Gap junctions- channels that allow materials to flow from the cytoplasms of adjacent cells (important in embryonic and cardiac cells)</p>
<p>Desmosomes- cell-to-cell adhesion complex that consists of cytoskeletal filaments from adjacent cells looped together</p>
<hr>
<ol>
<li>Which of the following correctly describes a function of the plant hormone gibberellin?</li>
</ol>
<p>(a) promotes fruit ripening
(b) promotes leaf elongation
(c) causes phototropisms
(d) stimulates cytokinesis and cell division</p>
<ol>
<li>Which animal phylum does NOT contain organisms that are true coelomates?</li>
</ol>
<p>(a) Nemotoda
(b) Annelida
(c) Mollusca
(d) Echinodermata</p>
<ol>
<li>E? I think? That makes cabbages grow 15 feet tall, right?</li>
<li>A for sure.</li>
</ol>
<p>Hey guys I have a really urgent question. I’m going through the Cliffs book to study for the AP exam, but I’m having a huge brain fart on Biological Diversity (all the taxonomy ****). Do they put much of that on the exam? Because unless the rest of the book builds on this I think I may be better off reading the rest of the book and coming back to this if I have more time left. I’m really just running late and this seems the least pertinent/time effective to study.</p>
<p>Thanks!</p>
<p>thanks mifune for the explanation!</p>
<p>@leafblade1354</p>
<p>Yes, the answers were B and A. (I think you meant to put B)</p>
<p>1.) A chemical is sprayed on a tomato plant which induces fruit production without pollination. All resulting tomatoes from this plant are seedless. The chemical most likely sprayed on the plant was:</p>
<p>(a) abscisic acid
(b) ethylene
(c) cytokinins
(d) auxin</p>
<p>2.) Which of the following is NOT found in the domain Bacteria:</p>
<p>(a) photosynthetic organisms
(b) peptidoglycan in cell walls
(c) introns in DNA
(d) viruses</p>
<p>
</p>
<p>Biological Diversity should consist of approximately 8% of the exam.</p>
<p>I don’t know 1.</p>
<p>I believe 2 is C.</p>
<p>I have not read Biological Diversity…and I’m halfway through animal systems…
which systems are most important? and what areas in Diversity are important?</p>